HLA-E and osteosarcoma: Another group downregulated NKG2A function in PBNKs and NK-92 cells by linking an anti-NKG2A antibody to an endoplasmic reticulum-retention domain, and achieved increased cytotoxicity against both HLA-E-positive and -negative cells derived from Ewing’s sarcoma, osteosarcoma and AML, as well as prolonged survival in immunodeficient mice expressing HLA-E tumors (50).